chore(test): fix various test failures caused by new pkgs

Author: STRML

.flowconfig

@@ -1,5 +1,6 @@
 [ignore]
 <PROJECT_ROOT>/node_modules/webpack-cli.*
+<PROJECT_ROOT>/node_modules/resolve.*
 
 [include]
 lib/

karma.conf.js

@@ -10,8 +10,6 @@ module.exports = function(config) {
     require('./webpack.config.js')({}, {}),
     {
       mode: 'development',
-      // Remove source maps: *speeeeeed*
-      devtool: false,
       cache: true,
       performance: {
         hints: false,
@@ -64,7 +62,10 @@ module.exports = function(config) {
 
     autoWatch: false,
 
-    browsers: ['Firefox', 'ChromeHeadless'],
+    browsers: [
+      'Firefox',
+      'ChromeHeadless'
+    ],
 
     singleRun: true,
   });

lib/DraggableCore.js

@@ -387,7 +387,8 @@ export default class DraggableCore extends React.Component<DraggableCoreProps, D
 
     // Snap to grid if prop has been provided
     if (Array.isArray(this.props.grid)) {
-      let deltaX = x - this.state.lastX, deltaY = y - this.state.lastY;
+      let deltaX = x - this.state.lastX || 0;
+      let deltaY = y - this.state.lastY || 0;
       [deltaX, deltaY] = snapToGrid(this.props.grid, deltaX, deltaY);
       x = this.state.lastX + deltaX, y = this.state.lastY + deltaY;
     }